In recent years there has been considerable interest and substantial development in the manufacture and use of precision-pattern micrometer and nanometer sized structures for use in a variety of different applications. The range of applications has come to include the use of these microstructures as diffraction gratings, femtoliter reaction wells, underlying supports for chromatography gels, as well as usages in the form of nanotubes, nanowires, quantum dots, microspheres, and nanometer-sized light-emitting diodes. Most of these micrometer and nanometer sized structures have been fabricated as ensembles--i.e., structures of varying size and poorly-defined positions rather than precisely patterned arrangements; and it is clearly the absence of precisely-defined microstructures in carefully prechosen arrangements and patterns which remains today the major obstacle inhibiting, if not directly preventing, further advancement in this field.
Some reasonably defined and complex-patterned microstructures have been produced using differing techniques. For example, laser-assisted chemical vapor deposition ("LCVD") has been recently used to fabricate some complex well-defined microstructures [Wallenberger, F. T., Science 267: 1274-1275 (1995)]. Also, precision microstructures have been fabricated by the creation of hydrophobic templates from photoresists for the deposition of self-assembled monolayers ("SAMs") on gold [Gorman et. al., Chem. Mater. 7:252-254 (1995); Singhvi et. al., Science 264:696-698 (1994)]. In addition, photoactivation techniques have also been used to fabricate some well-defined microstructures. As one representative example, photolithography has been used for information storage in photoconductive materials [Liu et. al. Science 261:897-899 (1993)]; in photoassembly of combinatorial libraries [Noble, D., Anal. Chem. 67:201A-204A (1995); Fodor et. al., Science 251: 767-773 (1991)]; and for site-selective covalent attachment of biomolecules [Yan et. al., J. Am. Chem. Soc. 115:814-816 (1993); Rozsnyai et. al., Angew. Chem. Int. Ed. Engl. 31:759-761 (1992)].
Although all of these reported fabrication techniques have been used successfully on occasion to produce micrometer scaled structures, all of these present substitive limitations and difficulties for the user. For instance, the LCVD technique can produce ultrapure materials, but has yet to be employed for any fabrication of polymeric compositions or polymer structures. These difficulties and limitations represent major obstacles and substantial hindrances in the presently known technology available to date for manufacturing precision pattern microstructures.
As a concurrent but essentially unrelated series of developments, the use of optical fiber strands and fiber optic arrays, alone and in combination with light energy absorbing dyes, has rapidly evolved for imaging and biochemical, and chemical analytical determinations, particularly within the last decade. The use of optical fibers for such purposes and techniques is described by Milanovich et. al., "Novel Optical Fiber Techniques For Medical Application", Proceedings of the SPIE 28th Annual International Technical Symposium On Optics And Electro-Optics, Volume 494, 1980; Seitz, W. R., "Chemical Sensors Based On Immobilized Indicators And Fiber Optics" in C.R.C. Critical Reviews In Analytical Chemistry, Vol.19,1988, pp. 135-173; Wolfbeis, O. S., "Fiber optical Fluorosensors In Analytical Chemistry" in Molecular Luminescence Spectroscopy, Methods And Applications (S. G. Schulman, editor), Wiley & Sons, New York (1988); Angel, S. M., Spectroscopy 2(4):38 (1987); and Walt et. al., "Chemical Sensors and Microinstrumentation", ACS Symposium Series, volume 403,1989, p. 252; Fiber Optical Chemical Sensors And Biosensors, (O. S. Wolfbeis, edition), CRC: Boca Raton, Fla., vol. 2, 1991, pp. 267-300; Biosensors With Fiber Optics, HUMANA, Clifton, N.J. 1991.
Optical fiber strands typically are glass or plastic extended rods having a small cross-sectional diameter. When light energy is projected into one end of the fiber strand (conventionally termed the "proximal end"), the angles at which the various light energy rays strike the surface are greater than the critical angle; and such rays are "piped" through the strand's length by successive internal reflections and eventually exit from the opposite end of the strand (conventionally termed the "distal end"). Typically, bundles of these strands are used collectively as imaging optic fiber arrays in a variety of different applications.
For making an imaging optical fiber into a chemical sensor, one or more light energy absorbing dyes are typically attached to the distal end of the optical fiber strand. The chemical sensor can then be used for both in-vitro and/or in-vivo applications. As used herein, light energy is photoenergy and is defined as electromagnetic radiation of any wavelength. Accordingly, the terms "light energy" and "photoenergy" include infrared, visible, and ultraviolet wavelengths conventionally employed in most optical instruments and apparatus; the term also includes the other spectral regions of X-ray and microwave wavelengths (although these are generally not used in conjunctions with optical fibers).
Many of the recent improvements employing optical fiber sensors in both qualitative and quantitative analytical determinations concern the desirability of depositing and/or immobilizing various light absorbing dyes at the intended distal end of an imaging optical fiber. For this purpose, a variety of different optical fiber chemical sensors and methods have been reported for specific analytical determinations and applications such as pH measurement, oxygen detection, and carbon dioxide analyses. These developments are exemplified by the following publications: Freeman et. al., Anal. Chem. 53:98 (1983); Lippitsch et. al., Anal. Chem. Acta. 205-1 (1988); Wolfbeis et. al., Anal. Chem. 60:2028 (1988); Jordan et. al., Anal. Chem. 59:437 (1987); Lubbers et. al., Sens. Actuators (1983); Munkholm et. al., Anal. Chem. 58:1427 (1986); Seitz, W. R. Anal. Chem. 56:16A-34A (1984); Peterson et. al., Anal. Chem. 52:864 (1980); Saari et. al., Anal. Chem. 54:821 (1982); Saari et. al., Anal. Chem. 55:667 (1983); Zhujun et. al., Anal. Chem. 56:2199 (1984); Collison, M. E. and M. E. Meyerhoff, Anal. Chem. 62:425A (1990); Demas, O. N. and B. A. DeGraff, Anal. Chem. 63:809A(1991); Seitz, W. R., CRC Crit. Rev. Anal. Chem. 19:135 (1988); Kopelman et. al., Science 258:778 (1992); Janata, J., Anal. Chem. 64:196R (1992); and Orella et. al., Anal. Chem. 64:2210 (1992); Janata, J., Anal. Chem. 66:207R (1994); Cohen, C. B., Anal. Chem. 65:169 (1993); Pantano, P., Anal. Chem. 67:481A (1995); Rozenzweig, Z., Anal. Chem. 67:2650 (1995); Kar, S., Anal. Chem. 64:2438 (1992); Wong, A., Anal. Chem. 64:1051 (1992); Vttamlal, M., Biotechnology 13:597 (1995); Barnard, S., Nature 353:338 (1991); Bronk, K., Anal. Chem. 66:3519 (1994). See also U.S. Pat. Nos. 4,822,746; 4,144,452; 4,495,293; 5,143,853; 5,244,636; 5,244,813; 5,250,264; 5,252,494; 5,254,477; 5,298,741; and the references cited within each of the issued patents.
Moreover, in view of the microcircuitry and enhanced television technology presently available, a variety of light image processing and analytical systems have come into existence in order to both enhance, analyze and mathematically process the light energies introduced to and emerging from the absorbing dyes in such optical analytical techniques. Typically, these systems provide components for image capture; data acquisition; data processing and analysis; and visual presentation to the user. Commercially available systems include the InCa.sup.++ system from Intracellular Imaging, Inc. (Cincinnati, Ohio) and the Videometric 150 system from Oncor, Inc. (Gaithersburg, Md.) Each of these systems may be combined with microscopes, cameras, and/or television monitors for automatic processing of all light energy determinations.
Despite all these developments in the use of fiber optic strands and arrays, both for imaging purposes and/or as chemical sensors, no bridge, linkage, suggestion, or query has been made or reported to date, insofar as is presently known, to utilize optical fiber technology for the potential fabrication of precision patterned, micrometer-sized, polymer structures. Accordingly, were a technique created which could employ optical fiber imaging methods and apparatus to generate micrometer sized polymer structures with precision-defined features, such an innovative method would be recognized as substantive achievement as well as a major advancement by all persons working in this technical field.